11, Feb, 2009
EWSN'09 TutorialThe wireless sensor networks standards and COTS landscape: can we get QoS and “calm technology”?
Tutorial at the 6th European Conference on Wireless Sensor Networks (EWSN'09), February 11th, Cork, Ireland.
We live in an increasingly ubiquitous and cyber-physical world. People increasingly use and depend on computers in a growing number and diversity of applications, most of which tend to be largely geographically distributed and tightly embedded in their physical environments. Ambient intelligence, assisted living, home and building automation, intelligent transportation systems are just some examples of application paradigms that are or will be soon interfering with our daily life. For this to happen at a global scale, standard and commercial-off-the-shelf (COTS) technology must be available and, most importantly, should be fully (or at least mostly) invisible to its users. The term calm technology was coined by Mark Weiser (The computer of the 21st Century, Scientific American, 1991), in his early visions on ubiquitous computing: the most profound technologies are those that disappear; they weave themselves into the fabric of everyday life until they are indistinguishable from it. Actually, common people do not want to know how a car, a pen or a computer works; they just want to be served properly, with the best quality possible. The first part of this tutorial will start with a snapshot of the evolution and trends in Information and Communication Technologies (ICTs). It will then browse the landscape of already established and emerging standard and COTS technology in the field of Wireless Sensor (and Actuator) Networks (WSNs), outlining and providing a comparison on issues such as: architectures (e.g. mesh, cluster-tree, multiple-tiered, hexagonal), routing and medium access control (MAC) protocol families, operating systems (e.g. TinyOS, Contiki, nano-RK), motes (e.g. MICAz, TelosB, iMote2), MEMS (MicroElectroMechanical Systems), RFIDs (active, semi-passive, passive) and communication protocol families (W/M/L/P/BAN). The second part will begin with a rationale for the need for Quality of Service (QoS) in WSNs. We address QoS at large sense and in a holistic perspective, instantiated in properties such as reliability, availability, maintainability, mobility, security, timeliness, system lifetime and cost. These quality attributes have been addressed separately, but satisfying all of them has not been achieved yet. We then explore how to devise a WSN communication architecture with the appropriate QoS levels, using standard and COTS technologies. The wireless communication protocols landscape is illustrated, outlining and comparing technologies such as the IEEE 802.11/15/16 family, ZigBee, WiBree, 6loWPAN, ISA100 and WirelessHART. We particularly address how the IEEE 802.15.4 and ZigBee protocols have been explored for supporting real-time and energy-efficient communications in WSNs. We conclude by identifying some major problems and challenges in WSNs.
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